Transcript 23-5 The Lungs - Berkeley County Schools

Chapter 23
The Respiratory
System
Lecture Presentation by
Lee Ann Frederick
University of Texas at Arlington
© 2015 Pearson Education, Inc.
23-1 Components of the Respiratory System
• Five Functions of the Respiratory System
1. Provides extensive gas exchange surface area
between air and circulating blood
2. Moves air to and from exchange surfaces of
lungs
3. Protects respiratory surfaces from outside
environment
4. Produces sounds
5. Participates in olfactory sense
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23-1 Components of the Respiratory System
• Organization of the Respiratory System
• The respiratory system is divided into:
• Upper respiratory system – above the larynx
• Lower respiratory system – below the larynx
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23-1 Components of the Respiratory System
• The Respiratory Tract
• Consists of a conducting portion
• From nasal cavity to terminal bronchioles
• Consists of a respiratory portion
• The respiratory bronchioles and alveoli
• Alveoli
• Are air-filled pockets within the lungs
• Where all gas exchange takes place
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Figure 23-1 The Structures of the Respiratory System.
Upper Respiratory System
Nose
Nasal cavity
Sinuses
Tongue
Pharynx
Esophagus
Lower Respiratory System
Clavicle
Larynx
Trachea
Bronchus
Bronchioles
Smallest bronchioles
Ribs
Right
lung
Left
lung
Alveoli
Diaphragm
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23-1 Components of the Respiratory System
• The Respiratory Epithelium
• For gases to exchange efficiently:
• Alveoli walls must be very thin (<1 µm)
• The Respiratory Mucosa
• Lines the conducting portion of respiratory system
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Figure 23-2a The Respiratory Epithelium of the Nasal Cavity and Conducting System.
Superficial view
SEM × 1647
a A surface view of the epithelium. The cilia of
the epithelial cells form a dense layer that
resembles a shag carpet. The movement of
these cilia propels mucus across the
epithelial surface.
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Figure 23-2c The Respiratory Epithelium of the Nasal Cavity and Conducting System.
Cilia
Lamina
propria
Nucleus of
columnar
epithelial cell
Mucous cell
Basement
membrane
Stem cell
c A sectional view of the respiratory epithelium, a
pseudostratified ciliated columnar epithelium.
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23-2 Upper Respiratory Tract
• The Nose
• Air enters the respiratory system
• Through nostrils or external nares
• Into nasal vestibule
• Nasal hairs
• Are in nasal vestibule
• Are the first particle filtration system
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23-2 Upper Respiratory Tract
• The Nasal Cavity
• The nasal septum
• Divides nasal cavity into left and right
• Superior portion of nasal cavity is the olfactory
region
• Provides sense of smell
• Mucous secretions from paranasal sinus and tears
• Clean and moisten the nasal cavityAir Flow
• Warm and humidify incoming air
• Trap particles
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23-2 Upper Respiratory Tract
• The Palates
• Hard palate
• Forms floor of nasal cavity
• Separates nasal and oral cavities
• Soft palate
• Extends posterior to hard palate
• Divides superior nasopharynx from lower pharynx
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23-2 Upper Respiratory Tract
• Air Flow
• Nasal cavity opens into nasopharynx through
internal nares
• The Nasal Mucosa
• Warms and humidifies inhaled air for arrival at
lower respiratory organs
• Breathing through mouth bypasses this important
step
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Figure 23-3a The Structures of the Upper Respiratory System.
Dorsum
nasi
Apex
Nasal
cartilages
External
nares
a The nasal cartilages and external
landmarks on the nose
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Figure 23-3b The Structures of the Upper Respiratory System.
Ethmoidal
air cell
Medial rectus
muscle
Cranial cavity
Frontal sinus
Right eye
Lens
Lateral rectus
muscle
Nasal septum
Perpendicular
plate of ethmoid
Vomer
Hard palate
Superior
nasal concha
Superior
meatus
Middle nasal
concha
Middle meatus
Maxillary sinus
Inferior nasal
concha
Inferior meatus
Tongue
Mandible
b A frontal section through the head, showing the
meatuses and the maxillary sinuses and air cells
of the ethmoidal labyrinth
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Figure 23-3c The Structures of the Upper Respiratory System (Part 2 of 2).
Frontal sinus
Nasal conchae
Nasal cavity
Superior
Middle
Internal nares
Inferior
Nasopharyngeal meatus
Nasal vestibule
Pharyngeal tonsil
Pharynx
External nares
Hard palate
Oral cavity
Nasopharynx
Oropharynx
Laryngopharynx
Tongue
Soft palate
Palatine tonsil
Mandible
Epiglottis
Lingual tonsil
Hyoid bone
Glottis
Thyroid cartilage
Cricoid cartilage
Trachea
Esophagus
Thyroid gland
c The nasal cavity and pharynx, as seen in sagittal section with the
nasal septum removed
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23-2 Upper Respiratory Tract
• The Pharynx
• A chamber shared by digestive and respiratory
systems
• Extends from internal nares to entrances to larynx
and esophagus
• Divided into three parts
1. The nasopharynx
2. The oropharynx
3. The laryngopharynx
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23-2 Upper Respiratory Tract
• The Nasopharynx
• Superior portion of pharynx
• Contains pharyngeal tonsils and openings to left
and right auditory tubes
• The Oropharynx
• Middle portion of pharynx
• Communicates with oral cavity
• The Laryngopharynx
• Inferior portion of pharynx
• Extends from hyoid bone to entrance of larynx and
esophagus
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23-3 The Larynx
• Air Flow
• From the pharynx enters the larynx
• A cartilaginous structure that surrounds the glottis,
which is a narrow opening
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23-3 The Larynx
• Cartilages of the Larynx
• Three large, unpaired cartilages form the larynx
1. Thyroid cartilage
• Anterior surface called laryngeal prominence, or Adam’s apple
• Ligaments attach to hyoid bone, epiglottis, and laryngeal
cartilages
2. Cricoid cartilage
• Forms posterior portion of larynx
• Ligaments attach to first tracheal cartilage
• Articulates with arytenoid cartilages
3. Epiglottis
• Composed of elastic cartilage
• Ligaments attach to thyroid cartilage and hyoid bone
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23-3 The Larynx
• Cartilage Functions
• Thyroid and cricoid cartilages support and protect:
• The glottis
• The entrance to trachea
• During swallowing:
• The larynx is elevated
• The epiglottis folds back over glottis
• Prevents entry of food and liquids into respiratory
tract
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23-3 The Larynx
• The Larynx Contains Three Pairs of Smaller
Hyaline Cartilages
1. Arytenoid cartilages
2. Corniculate cartilages
3. Cuneiform cartilages
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Figure 23-4a The Anatomy of the Larynx.
Epiglottis
Lesser cornu
Hyoid bone
Thyrohyoid
ligament
Laryngeal
prominence
Thyroid
cartilage
Larynx
Cricothyroid
ligament
Cricoid cartilage
Cricotracheal
ligament
Trachea
Tracheal
cartilages
a
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Anterior view
Figure 23-4b The Anatomy of the Larynx.
Epiglottis
Vestibular
ligament
Corniculate
cartilage
Vocal ligament
Thyroid
cartilage
Arytenoid
cartilage
Cricoid cartilage
Tracheal
cartilages
b
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Posterior view
Figure 23-4c The Anatomy of the Larynx.
Hyoid bone
Epiglottis
Thyroid
cartilage
Vestibular
ligament
Corniculate
cartilage
Vocal ligament
Arytenoid
cartilage
Cricoid
cartilage
Cricothyroid ligament
Tracheal
cartilages
Cricotracheal ligament
ANTERIOR
POSTERIOR
c
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Sagittal section
23-3 The Larynx
• Cartilage Functions
• Corniculate and arytenoid cartilages function in:
• Opening and closing of glottis
• Production of sound
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23-3 The Larynx
• Ligaments of the Larynx
• Vestibular ligaments and vocal ligaments
• Extend between thyroid cartilage and arytenoid
cartilages
• Are covered by folds of laryngeal epithelium that
project into glottis
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23-3 The Larynx
• The Vestibular Ligaments
• Lie within vestibular folds
• Which protect delicate vocal folds
• Sound Production
• Air passing through glottis
• Vibrates vocal folds
• Produces sound waves
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23-3 The Larynx
• Sound Production
• Sound is varied by:
• Tension on vocal folds
• Vocal folds involved with sound are known as vocal
cords
• Voluntary muscles (position arytenoid cartilage
relative to thyroid cartilage)
• Speech is produced by:
• Phonation
• Sound production at the larynx
• Articulation
• Modification of sound by other structures
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Figure 23-5a The Glottis and Surrounding Structures.
Corniculate
cartilage
POSTERIOR
Cuneiform
cartilage
Aryepiglottic
fold
Vestibular
fold
Vocal fold
of glottis
Epiglottis
Root of tongue
ANTERIOR
a
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Glottis in the closed position.
Figure 23-5b The Glottis and Surrounding Structures.
POSTERIOR
Corniculate cartilage
Cuneiform cartilage
Glottis (open)
Rima glottidis
Vocal fold
Vestibular fold
Epiglottis
ANTERIOR
b
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Glottis in the open position.
Figure 23-5c The Glottis and Surrounding Structures.
Corniculate cartilage
Cuneiform cartilage
Glottis (open)
Rima glottidis
Vocal fold
Vestibular fold
Vocal nodule
Epiglottis
c Photograph taken with a laryngoscope
positioned within the oropharynx,
superior to the larynx. Note the
abnormal vocal nodule.
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23-3 The Larynx
• The Laryngeal Musculature
• The larynx is associated with:
1. Muscles of neck and pharynx
2. Intrinsic muscles
• Control vocal folds
• Open and close glottis
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23-4 The Trachea
• The Trachea
• Also called the windpipe
• Extends from the cricoid cartilage into
mediastinum
• Where it branches into right and left pulmonary
bronchi
• The submucosa
• Beneath mucosa of trachea
• Contains mucous glands
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Figure 23-6b The Anatomy of the Trachea.
Esophagus
Trachealis
muscle
Thyroid
gland
Lumen of
trachea
Respiratory
epithelium
Tracheal
cartilage
The trachea
b A cross-sectional view
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LM × 3
23-4 The Trachea
• The Tracheal Cartilages
• 15–20 tracheal cartilages
• Strengthen and protect airway
• Discontinuous where trachea contacts esophagus
• Ends of each tracheal cartilage are connected by:
• An elastic ligament and trachealis muscle
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23-4 The Trachea
• The Primary Bronchi
• Right and Left Primary Bronchi
• Separated by an internal ridge (the carina)
• The Right Primary Bronchus
• Is larger in diameter than the left
• Descends at a steeper angle
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Figure 23-6a The Anatomy of the Trachea.
Hyoid
bone
Larynx
Trachea
Tracheal
cartilages
Location of carina
(internal ridge)
Root of
right lung
Lung
tissue
RIGHT LUNG
a
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Root of
left lung
Primary
bronchi
Secondary
bronchi
LEFT LUNG
A diagrammatic anterior view showing the plane of section
for part (b)
23-4 The Trachea
• The Primary Bronchi
• Hilum
• Where pulmonary nerves, blood vessels,
lymphatics enter lung
• Anchored in meshwork of connective tissue
• The root of the lung
• Complex of connective tissues, nerves, and
vessels in hilum
• Anchored to the mediastinum
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23-5 The Lungs
• The Lungs
• Left and right lungs
• Are in left and right pleural cavities
• The base
• Inferior portion of each lung rests on superior
surface of diaphragm
• Lobes of the lungs
• Lungs have lobes separated by deep fissures
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23-5 The Lungs
• Lobes and Surfaces of the Lungs
• The right lung has three lobes
• Superior, middle, and inferior
• Separated by horizontal and oblique fissures
• The left lung has two lobes
• Superior and inferior
• Separated by an oblique fissure
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23-5 The Lungs
• Lung Shape
• Right lung
• Is wider
• Is displaced upward by liver
• Left lung
• Is longer
• Is displaced leftward by the heart forming the
cardiac notch
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Figure 23-7a The Gross Anatomy of the Lungs (Part 2 of 2).
Boundary between
right and left
pleural cavities
Superior lobe
Left lung
Right lung
Superior lobe
Oblique fissure
Horizontal fissure
Middle lobe
Fibrous layer
of pericardium
Inferior lobe
Oblique fissure
Inferior lobe
Falciform ligament
Liver,
right lobe
Liver,
left lobe
a Thoracic cavity, anterior view
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Cut edge of
diaphragm
Figure 23-7b The Gross Anatomy of the Lungs.
b
Lateral Surfaces
The curving anterior and lateral
surfaces of each lung follow the
inner contours of the rib cage.
Apex
Apex
Superior
lobe
ANTERIOR
Superior lobe
Horizontal fissure
Middle
lobe
Oblique fissure
Inferior
lobe
The cardiac notch
accommodates the
pericardial cavity,
which sits to the left
of the midline.
Oblique
fissure
Inferior
lobe
Base
Right lung
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Base
Left lung
Figure 23-7c The Gross Anatomy of the Lungs.
c
Medial Surfaces
The medial surfaces, which contain the
hilum, have more irregular shapes. The
medial surfaces of both lungs have grooves
that mark the positions of the great
vessels of the heart.
Apex
Superior
lobe
Pulmonary artery
Horizontal fissure
Middle
lobe
POSTERIOR
Inferior
lobe
Right lung
Groove
for aorta
Pulmonary
artery
Pulmonary
veins
Inferior
lobe
Oblique
fissure
Bronchus
Base
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Superior
lobe
Bronchus
The hilum of the lung is
a groove that allows
passage of the primary
bronchi, pulmonary
vessels, nerves, and
lymphatics.
Pulmonary veins
Oblique fissure
Apex
Diaphragmatic
surface
Base
Left lung
23-5 The Lungs
• The Bronchi
• The Bronchial Tree
• Is formed by the primary bronchi and their
branches
• Extrapulmonary Bronchi
• The left and right bronchi branches outside the
lungs
• Intrapulmonary Bronchi
• Branches within the lungs
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23-5 The Lungs
• A Primary Bronchus
• Branches to form secondary bronchi (lobar
bronchi)
• One secondary bronchus goes to each lobe
• Secondary Bronchi
• Branch to form tertiary bronchi (segmental
bronchi)
• Each segmental bronchus
• Supplies air to a single bronchopulmonary
segment
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23-5 The Lungs
• Bronchopulmonary Segments
• The right lung has 10
• The left lung has 8 or 9
• Bronchial Structure
• The walls of primary, secondary, and tertiary
bronchi
• Contain progressively less cartilage and more
smooth muscle
• Increased smooth muscle tension affects airway
constriction and resistance
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23-5 The Lungs
• Bronchitis
• Inflammation of bronchial walls
• Causes constriction and breathing difficulty
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23-5 The Lungs
• The Bronchioles
• Each tertiary bronchus branches into multiple
bronchioles
• Bronchioles branch into terminal bronchioles
• One tertiary bronchus forms about 6500 terminal
bronchioles
• Bronchiole Structure
• Bronchioles
• Have no cartilage
• Are dominated by smooth muscle
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23-5 The Lungs
• Autonomic Control
• Regulates smooth muscle
• Controls diameter of bronchioles
• Controls airflow and resistance in lungs
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23-5 The Lungs
• Bronchodilation
• Dilation of bronchial airways
• Caused by sympathetic ANS activation
• Reduces resistance
• Bronchoconstriction
• Constricts bronchi
• Caused by:
• Parasympathetic ANS activation
• Histamine release (allergic reactions)
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23-5 The Lungs
• Asthma
• Excessive stimulation and bronchoconstriction
• Stimulation severely restricts airflow
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23-5 The Lungs
• Pulmonary Lobules
• Trabeculae
• Fibrous connective tissue partitions from root of
lung
• Contain supportive tissues and lymphatic vessels
• Branch repeatedly
• Divide lobes into increasingly smaller
compartments
• Pulmonary lobules are divided by the smallest
trabecular partitions (interlobular septa)
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Figure 23-9a The Bronchi, Lobules, and Alveoli of the Lung.
LEFT
RIGHT
Bronchopulmonary
segments of
superior lobe
(3 segments)
Bronchopulmonary
segments of
superior lobe
(4 segments)
Bronchopulmonary
segments of
inferior lobe
(5 segments)
Bronchopulmonary
segments of
middle lobe
(2 segments)
Bronchopulmonary
segments of
inferior lobe
(5 segments)
a Anterior view of the lungs, showing
the bronchial tree and its divisions
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Figure 23-9b The Bronchi, Lobules, and Alveoli of the Lung.
Trachea
Cartilage
plates
Left primary
bronchus
Visceral pleura
Secondary
bronchus
Tertiary bronchi
Smaller
bronchi
Bronchioles
Terminal
bronchiole
Alveoli in a
pulmonary
lobule
Respiratory
bronchiole
Bronchopulmonary segment
b The branching pattern of bronchi
in the left lung, simplified
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Figure 23-9c The Bronchi, Lobules, and Alveoli of the Lung.
Respiratory epithelium
Bronchiole
Bronchial artery (red),
vein (blue), and
nerve (yellow)
Branch of pulmonary
artery
Smooth muscle
around terminal
bronchiole
Terminal bronchiole
Branch of
pulmonary
vein
Respiratory
bronchiole
Elastic fibers
around alveoli
Arteriole
Capillary
beds
Alveolar
duct
Lymphatic
vessel
Alveoli
Alveolar sac
Interlobular
septum
c The structure of a single pulmonary lobule,
part of a bronchopulmonary segment
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Figure 23-9d The Bronchi, Lobules, and Alveoli of the Lung.
Alveoli
Alveolar sac
Alveolar duct
Lung tissue
SEM × 125
d SEM of lung tissue showing the
appearance and organization of
the alveoli
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23-5 The Lungs
• Pulmonary Lobules
• Each terminal bronchiole delivers air to a single
pulmonary lobule
• Each pulmonary lobule is supplied by pulmonary
arteries and veins
• Each terminal bronchiole branches to form several
respiratory bronchioles, where gas exchange
takes place
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23-5 The Lungs
• Alveolar Ducts and Alveoli
• Respiratory bronchioles are connected to alveoli
along alveolar ducts
• Alveolar ducts end at alveolar sacs
• Common chambers connected to many individual
alveoli
• Each alveolus has an extensive network of
capillaries
• Surrounded by elastic fibers
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Figure 23-10a Alveolar Organization.
Respiratory bronchiole
Smooth
muscle
Elastic
fibers
Capillaries
a The basic structure of the distal end of a single
lobule. A network of capillaries, supported by
elastic fibers, surrounds each alveolus. Respiratory
bronchioles are also wrapped by smooth muscle
cells that can change the diameter of these airways.
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Alveolar duct
Alveolus
Alveolar
sac
Figure 23-10b Alveolar Organization.
Alveoli
Respiratory
bronchiole
Alveolar
sac
Arteriole
Histology of the lung
b Low-power micrograph of lung tissue.
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LM × 14
23-5 The Lungs
• Respiratory Distress Syndrome
• Difficult respiration
• Due to alveolar collapse
• Caused when type II pneumocytes do not produce
enough surfactant
• Respiratory Membrane
• The thin membrane of alveoli where gas exchange
takes place
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23-5 The Lungs
• Diffusion
• Across respiratory membrane is very rapid
• Because distance is short
• Gases (O2 and CO2) are lipid soluble
• Inflammation of Lobules
• Also called pneumonia
• Causes fluid to leak into alveoli
• Compromises function of respiratory membrane
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23-5 The Lungs
• Blood Supply to the Lungs
• Respiratory exchange surfaces receive blood
• From arteries of pulmonary circuit
• A capillary network surrounds each alveolus
• As part of the respiratory membrane
• Blood from alveolar capillaries
• Passes through pulmonary venules and veins
• Returns to left atrium
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23-5 The Lungs
• The Pleural Cavities and Pleural Membranes
• Two pleural cavities
• Are separated by the mediastinum
• Each pleural cavity:
• Holds a lung
• Is lined with a serous membrane (the pleura)
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23-5 The Lungs
• The Pleura
• Consists of two layers
1. Parietal pleura
2. Visceral pleura
• Pleural fluid
• Lubricates space between two layers
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23-6 Introduction to Gas Exchange
• Respiration
• Refers to two integrated processes
1. External respiration
• Includes all processes involved in exchanging O2
and CO2 with the environment
2. Internal respiration
• Result of cellular respiration
• Involves the uptake of O2 and production of CO2
within individual cells
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23-6 Introduction to Gas Exchange
• Abnormal External Respiration Is Dangerous
• Hypoxia
• Low tissue oxygen levels
• Anoxia
• Complete lack of oxygen
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23-7 Pulmonary Ventilation
• Pulmonary Ventilation
• Is the physical movement of air in and out of
respiratory tract
• Provides alveolar ventilation
• The Movement of Air
• Atmospheric pressure
• The weight of air
• Has several important physiological effects
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23-7 Pulmonary Ventilation
• Pressure and Airflow to the Lungs
• Air flows from area of higher pressure to area of
lower pressure
• A Respiratory Cycle
• Consists of:
• An inspiration (inhalation)
• An expiration (exhalation)
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23-7 Pulmonary Ventilation
• The Respiratory Cycle
• Cyclical changes in intrapleural pressure operate
the respiratory pump
• Which aids in venous return to heart
• Tidal Volume (VT)
• Amount of air moved in and out of lungs in a single
respiratory cycle
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23-7 Pulmonary Ventilation
• Injury to the Chest Wall
• Pneumothorax allows air into pleural cavity
• Atelectasis (also called a collapsed lung) is a
result of pneumothorax
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Figure 23-14 Pressure and Volume Changes during Inhalation and Exhalation.
INHALATION EXHALATION
Intrapulmonary
pressure
(mm Hg)
Trachea
+2
+1
a Changes in intrapulmonary
0
pressure during a single
respiratory cycle
−1
Bronchi
Intrapleural
pressure
(mm Hg)
Lung
−2
−3
b Changes in intrapleural
−4
Diaphragm
pressure during a single
respiratory cycle
−5
Right pleural
cavity
Left pleural
cavity
−6
Tidal
volume
(mL)
500
c A plot of tidal volume, the
250
amount of air moving into
and out of the lungs during a
single respiratory cycle
0
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1
2
3
Time (sec)
4
23-7 Pulmonary Ventilation
• The Respiratory Muscles
• Most important are:
• The diaphragm
• External intercostal muscles of the ribs
• Accessory respiratory muscles
• Activated when respiration increases significantly
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23-7 Pulmonary Ventilation
• Muscles Used in Inhalation
• Diaphragm
• Contraction draws air into lungs
• 75 percent of normal air movement
• External intercostal muscles
• Assist inhalation
• 25 percent of normal air movement
• Accessory muscles assist in elevating ribs
•
•
•
•
Sternocleidomastoid
Serratus anterior
Pectoralis minor
Scalene muscles
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Figure 23-15 Respiratory Muscles and Pulmonary Ventilation (Part 1 of 4).
The Respiratory Muscles
The most important skeletal muscles involved in respiratory movements are the
diaphragm and the external intercostals. These muscles are the primary
respiratory muscles and are active during normal breathing at rest. The
accessory respiratory muscles become active when the depth and frequency
of respiration must be increased markedly.
Accessory
Respiratory Muscles
Sternocleidomastoid
muscle
Scalene muscles
Pectoralis minor
muscle
Serratus anterior
muscle
Primary
Respiratory Muscles
Diaphragm
Primary
Respiratory Muscles
External intercostal
muscles
Accessory
Respiratory Muscles
Internal intercostal
muscles
Transversus thoracis
muscle
External oblique
muscle
Rectus abdominis
Internal oblique
muscle
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23-7 Pulmonary Ventilation
• Modes of Breathing
• Respiratory movements are classified
• By pattern of muscle activity
• Quiet breathing
• Forced breathing
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23-7 Pulmonary Ventilation
• Quiet Breathing (Eupnea)
• Involves active inhalation and passive exhalation
• Diaphragmatic breathing or deep breathing
• Is dominated by diaphragm
• Costal breathing or shallow breathing
• Is dominated by rib cage movements
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23-7 Pulmonary Ventilation
• Elastic Rebound
• When inhalation muscles relax
• Elastic components of muscles and lungs recoil
• Returning lungs and alveoli to original position
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23-7 Pulmonary Ventilation
• Forced Breathing (Hyperpnea)
• Involves active inhalation and exhalation
• Assisted by accessory muscles
• Maximum levels occur in exhaustion
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23-7 Pulmonary Ventilation
• Respiratory Rates and Volumes
• Respiratory system adapts to changing oxygen
demands by varying:
• The number of breaths per minute (respiratory
rate)
• The volume of air moved per breath (tidal volume)
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23-7 Pulmonary Ventilation
• The Respiratory Minute Volume (VE)
• Amount of air moved per minute
• Is calculated by:
respiratory rate  tidal volume
• Measures pulmonary ventilation
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23-7 Pulmonary Ventilation
• Alveolar Ventilation (VA)
• Only a part of respiratory minute volume reaches
alveolar exchange surfaces
• Volume of air remaining in conducting passages is
anatomic dead space
• Alveolar ventilation is the amount of air reaching
alveoli each minute
• Calculated as:
(tidal volume  anatomic dead space)  respiratory rate
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23-7 Pulmonary Ventilation
• Relationships among VT, VE, and VA
• Determined by respiratory rate and tidal volume
• For a given respiratory rate:
• Increasing tidal volume increases alveolar
ventilation rate
• For a given tidal volume:
• Increasing respiratory rate increases alveolar
ventilation
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23-7 Pulmonary Ventilation
• Respiratory Performance and Volume
Relationships
• Total lung volume is divided into a series of
volumes and capacities useful in diagnosing
problems
• Four Pulmonary Volumes
1.
2.
3.
4.
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Resting tidal volume (Vt)
Expiratory reserve volume (ERV)
Residual volume
Inspiratory reserve volume (IRV)
23-7 Pulmonary Ventilation
• Resting Tidal Volume (Vt)
• In a normal respiratory cycle
• Expiratory Reserve Volume (ERV)
• After a normal exhalation
• Residual Volume
• After maximal exhalation
• Minimal volume (in a collapsed lung)
• Inspiratory Reserve Volume (IRV)
• After a normal inspiration
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23-7 Pulmonary Ventilation
• Four Calculated Respiratory Capacities
1. Inspiratory capacity
• Tidal volume + inspiratory reserve volume
2. Functional residual capacity (FRC)
• Expiratory reserve volume + residual volume
3. Vital capacity
• Expiratory reserve volume + tidal volume +
inspiratory reserve volume
4. Total lung capacity
• Vital capacity + residual volume
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Figure 23-16 Pulmonary Volumes and Capacities.
Pulmonary Volumes and Capacities (adult male)
6000
Sex Differences
Tidal volume
(VT = 500 mL)
Inspiratory
capacity
Inspiratory
reserve
volume (IRV)
Volume (mL)
Total lung
capacity
Expiratory
reserve
volume (ERV)
Functional
residual
capacity
(FRC)
1200
0
Residual
volume
Time
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1900
500
500
ERV 1000
700
Residual volume 1200
1100
VT
Total lung capacity 6000 mL
2200
Minimal volume
(30–120 mL)
IRV 3300
Vital
capacity
Vital
capacity
2700
Females
Males
4200 mL
Inspiratory
capacity
Functional
residual
capacity
23-10 Control of Respiration
• Sudden Infant Death Syndrome (SIDS)
• Disrupts normal respiratory reflex pattern
• May result from connection problems between
pacemaker complex and respiratory centers of the
brain (medulla oblongata)
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23-10 Control of Respiration
• Hypercapnia and Hypocapnia
• Hypoventilation is a common cause of
hypercapnia
• Abnormally low respiration rate
• Allows CO2 buildup in blood
• Excessive ventilation, hyperventilation, results in
abnormally low PCO (hypocapnia)
2
• Stimulates chemoreceptors to decrease respiratory
rate
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23-10 Control of Respiration
• Apnea
• A period of suspended respiration
• Normally followed by explosive exhalation to clear
airways
• Sneezing and coughing
• Laryngeal Spasm
• Temporarily closes airway
• To prevent foreign substances from entering
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